Interconnect for packaging semiconductor dice and fabricating BGA packages

ABSTRACT

An interconnect for BGA packages, a BGA package fabricated using the interconnect, and a method for fabricating BGA packages using the interconnect, are provided. The interconnect includes multiple polymer substrates on which patterns of conductors are formed. Each substrate can be used to fabricate a BGA package. The conductors on the substrates include end portions having bonding vias formed therethrough in alignment with access openings in the substrates. During fabrication of the BGA packages, the bonding vias allow the conductors to be bonded to bond pads on semiconductor dice by forming metal bumps on the bonding vias and bond pads. The access openings in the substrates provide access to the bonding vias and bond pads for a bonding tool configured to form the metal bumps. In addition to the bonding vias, the conductors include ball bonding pads configured for attaching ball contacts, such as solder balls, to the conductors and substrates. The completed BGA package includes a substrate adhesively bonded to a semiconductor die; conductors with bonding vias on the substrate; metal bumps in the bonding vias bonding the conductors to bond pads on the die; and an area array of ball contacts attached to the conductors and substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 09/206,116 filedon Dec. 4, 1998, U.S. Pat. No. 6,232,666.

FIELD OF THE INVENTION

This invention relates generally to semiconductor packaging andspecifically to an interconnect for packaging semiconductor dice, and toan improved BGA package fabricated using the interconnect.

BACKGROUND OF THE INVENTION

One type of semiconductor package is referred to as a BGA package. BGApackages were developed to provide a higher lead count, and a smallerfoot print, than conventional plastic or ceramic semiconductor packages.A BGA package includes an array of external ball contacts, such assolder balls, that permit the package to be surface mounted to a printedcircuit board (PCB) or other electronic component. Some BGA packageshave a foot print that is about the size of the die contained in thepackage. These BGA packages are also known as chip scale packages.

As BGA packages are made smaller, and with higher lead counts, theelectrical connections between the die and the ball contacts for thepackage become more difficult to make. The component of the package thatmakes the electrical connections between the die and package issometimes referred to as an interconnect.

One type of prior art BGA package uses an interconnect in the form of amulti layered polymer tape, such as TAB tape. The polymer tape can beprovided as a “strip” or “coupon” of material for packaging several diceat a time. Typically, the polymer tape comprises a polyimide substratehaving patterns of metal conductors formed thereon. In addition,portions of the conductors can comprise beam leads, formed in aconfiguration which allows the beam leads to be bonded to the bond padson the die.

FIG. 1 illustrates a prior art BGA package 10. The BGA package 10includes: a semiconductor die 12; a polymer tape 14 bonded to a face ofthe die 12; and an encapsulant 16 bonded to the face and sides of thedie 12. The BGA package 10 also includes an adhesive layer 18 forbonding the polymer tape 14 to the die 12. In addition, the BGA package10 includes a dense array of ball contacts 20 formed on the polymer tape14. A solder mask 15 locates and electrically insulates the ballcontacts 20 from one another.

The polymer tape 14 includes a pattern of metal conductors 21 that formseparate electrical paths between bond pads 24 on the die 12 and theball contacts 20. The conductors 36 include ball bonding pads 23 thatare bonded to the ball contacts 20, and beam leads 22 that are bonded tothe bond pads 24 on the die 12. The beam leads 22 are also encapsulatedin the encapsulant 16.

A representative process for forming the BGA package 10 includes theinitial step of bonding one or more dice 12 to a strip of the polymertape 14. The beam leads 22 can then be bonded to the device bond pads24. Next, the encapsulant 16 can be formed, and the ball contacts 20bonded to the ball bonding pads 23. The individual BGA packages 10 canthen be singulated from the strip of polymer tape 14 and tested.

Typically, a thermosonic bonding process, using gold, or gold platedmaterials, is employed to bond the beam leads 22 to the bond pads 24.Specialized bonding tools are required to make the bonds between thebeam leads 22 and the bond pads 24. In addition, the beam leads 22 aresubjected to stresses from the bonding and encapsulation processes, andduring subsequent use of the BGA package 10. These stresses can causethe bonds to weaken and the beam leads to separate from the bond pads24.

Because of these and other deficiencies in conventional BGA packages,improvements in BGA packages, and in methods for fabricating BGApackages, would be welcomed in the art. The present invention isdirected to an improved interconnect for constructing BGA packages. Theinterconnect is constructed to facilitate formation of bondedconnections with the die, and to provide improved bonded connectionswith the die.

SUMMARY OF THE INVENTION

In accordance with the present invention, an improved interconnect forsemiconductor dice, an improved BGA package, and an improved method forfabricating BGA packages, are provided.

The interconnect comprises a polymer substrate, and a pattern ofconductors formed on the substrate. In the illustrative embodiment theinterconnect contains multiple polymer substrates that are subsequentlysingulated into individual BGA packages. The conductors include endportions having bonding vias for making bonded electrical connectionswith bond pads on a semiconductor die. A location of the end portionsand bonding vias exactly matches a location of the bond pads on the die,permitting alignment for the bonding process. In addition, the endportions and bonding vias overhang corresponding openings in the polymersubstrate, permitting access for a bonding tool for performing thebonding process. The conductors also include ball bonding pads, whichallow ball contacts to be bonded to the conductors, and attached to thepolymer substrate.

For fabricating a BGA package, the polymer substrate can be adhesivelybonded to the die with the bonding vias on the conductors, and theopenings in the polymer substrate, aligned with the bond pads on thedie. Metal bumps can then be formed in the bonding vias to physicallyand electrically attach the end portions of the conductors to the bondpads on the die. The metal bumps can be formed using a bonding tool of awire bonding apparatus, or using a solder ball bumper apparatus.Alternately, the metal bumps can comprise solder bumps of a bumpedsemiconductor die that are reflowed into the bonding vias. Followingforming of the metal bumps, ball contacts, such as solder balls, can bebonded to the ball bonding pads on the conductors.

The completed BGA package includes the semiconductor die, the polymersubstrate adhesively bonded to the face of the die, and the metal bumpsin the bonding vias bonding the conductors on the polymer substrate tothe bond pads on the die. The BGA package also includes an array of ballcontacts bonded to the ball bonding pads on the conductors. With thisconstruction, the conductors establish electrical communication betweenthe bond pads on the die, and the ball contacts on the polymersubstrate. Further, the metal bumps in the bonding vias physically andelectrically bond the conductors to the bond pads on the die.

The method for fabricating the BGA package includes the steps of:providing a polymer substrate comprising a pattern of conductors and apattern of openings to the conductors; providing the conductors withbonding vias on first end portions thereof aligned with the openings inthe polymer substrate; providing the conductors with ball bonding padson second end portions thereof; adhesively bonding the polymer substrateto a semiconductor die with the bonding vias on the conductors alignedwith bond pads on the die; forming metal bumps through the openings inthe polymer substrate onto the bonding vias on the conductors tophysically and electrically attach the conductors to the bond pads; andthen bonding ball contacts to the ball bonding pads on the conductors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged schematic cross sectional view of a prior art BGApackage;

FIG. 2 is a plan view of an interconnect constructed in accordance withthe invention;

FIG. 2A is an enlarged portion of FIG. 2 taken along section line 2A ofFIG. 2;

FIG. 2B is an enlarged portion of FIG. 2A taken along section line 2B ofFIG. 2A;

FIG. 2C is an enlarged portion of FIG. 2B taken along section line 2C ofFIG. 2B;

FIG. 2D is a cross sectional view taken along section line 2D—2D of FIG.2C;

FIG. 2E is a cross sectional view taken along section line 2E—2E of FIG.2C;

FIG. 2F is a cross sectional view taken along section line 2F—2F of FIG.2B;

FIGS. 3A-3D are schematic cross sectional views illustrating steps in amethod for fabricating a BGA package in accordance with the invention;

FIGS. 4A-4C are schematic cross sectional views illustrating steps in analternate embodiment method for fabricating a BGA package in accordancewith the invention;

FIG. 5A is a bottom view of a BGA package constructed in accordance withthe invention;

FIG. 5B is a side elevation view of the package of FIG. 5A;

FIG. 5C is an enlarged cross sectional view taken along section line5C—5C of FIG. 5B;

FIG. 5D is an enlarged portion of FIG. 5C taken along section line 5D—5Dof FIG. 5C.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 2-2F, an interconnect 30 constructed in accordancewith the invention, includes a plurality of polymer substrates 32, and aplurality of patterns of conductors 36 formed on the substrates 32. Aswill be further explained, the polymer substrates 32 and patterns ofconductors 36, can be used to fabricate multiple BGA packages 38 (FIG.5A). The polymer substrates 32 comprise segments of the interconnect 30that will subsequently be singulated into separate BGA packages 38 (FIG.5A).

In the illustrative embodiment, the interconnect 30 comprises a strip ofmaterial similar in size and shape to a conventional semiconductor leadframe. The polymer substrates 32 correspond to die mounting paddles on aconventional lead frame. Alternately, the interconnect 30 can be shapedas a coupon of material, with the outline and location of the polymersubstrates 32 corresponding to the outline and location of semiconductordice contained on a semiconductor wafer. The coupon can be shaped topackage a desired number of dice on the wafer, up to all of the dice onthe wafer.

Suitable materials for the interconnect 30 and polymer substrates 32include polyimide, polyester, epoxy, urethane, polystyrene, silicone andpolycarbonate. A representative thickness for the interconnect 30 andpolymer substrates 32 can be from about 25 to 400 μm.

As shown in FIG. 2, the interconnect 30 includes a plurality of indexingopenings 40 formed therethrough proximate to longitudinal edges thereof.The indexing openings 40 permit the interconnect 30 to be handled byautomated transfer mechanisms associated with various apparatuses thatwill be used during fabrication of the BGA packages 38 (FIG. 5A), suchas chip bonders and ball bonders.

The patterns of conductors 36 can be formed on the substrates 32 using asubtractive process. For example, the conductors 36 can comprise a metalfoil, bonded to the polymer substrates 32, then photo patterned, andetched. Alternately, a metal layer can be blanket deposited on thepolymer substrates 32, such as by electrodeposition, then photopatterned, and etched to form the conductors 36. Using a subtractiveprocess a width “w” and spacing “s” of the conductors can be as small asabout 0.075 mm. As another alternative, the patterns of conductors 36can be formed using an additive process by deposition, or printing, of ametal through a mask. Using an additive process a width “w” and spacing“s” of the conductors can be as small as about 0.030 mm.

Preferably, the conductors 36 comprise a highly conductive metal, suchas copper, plated copper, gold, gold plated metals, nickel, or an alloysuch as Ni—Pd. By way of example, the conductors 36 can be formed with athickness of from 1 μm to 35 μm.

As shown in FIG. 2B, each conductor 36 includes a bonding via 42 formedon a first end thereof. The bonding vias 42 are configured to makeelectrical connections with bond pads 46 (FIG. 5D) formed on a face of asemiconductor die 34 (FIG. 5D). In addition, each conductor 36 includesa ball bonding pad 44 on a second end thereof. The ball bonding pads 44are configured for bonding ball contacts 56 (FIG. 5A) to the polymersubstrates 32.

As shown in FIG. 2C, the bonding vias 42 comprise through openings inthe conductors 36. In the illustrative embodiment, the conductors 36include enlarged end portions 50 wherein the bonding vias 42 are formed.However, it is to be understood that the invention can be practiced byforming the bonding vias 42 in conductors having end portions with thesame width as the remainder of the conductors. Also, in the illustrativeembodiment, the end portions 50 and bonding vias 42 both have agenerally square shaped peripheral configuration. However, othergeometrical configurations such as circular, triangular and oval can beemployed for the bonding vias 42.

A peripheral size of each end portion 50 is about the same as theperipheral size of a bond pad 46 (FIG. 5D) on the die 34 (FIG. 5A). Byway of example, the end portions 50 can be from about 0.05 mm (50 μm) to0.20 mm (200 μm) on a side and spaced by about the same amount. Thebonding vias 42 are sized to fit within the end portions 50.Accordingly, a continuous square metal segment 52 encloses and definesthe periphery of each bonding via 42. In addition, a continuouselectrical path is provided through the conductors 36 to the squaremetal segments 52.

A location and spacing of the end portions 50 and bonding vias 42,exactly matches a location and spacing, of the bond pads 46 (FIG. 5D) onthe die 34 (FIG. 5D). In the illustrative embodiment, the bond pads 46(FIG. 5D) are formed in a single row along a center line of the die 34,in the manner of a leads over chip die. Alternately, the location andpattern of the end portions 50, and bonding vias 42, can match otherbond pad configurations, such as along the ends, or edges, of the die34.

As shown in FIGS. 2C, 2D and 2E, the polymer substrates 32 includepatterns of access openings 54 that correspond to the locations of theend portions 50 and bonding vias 42. As will be further explained, theaccess openings 54 permit access for a bonding tool to form metal bumps60 (FIG. 5D) in the bonding vias 42 (FIG. 2D), for bonding the endportions 50 of the conductors 36 to the bond pads 46 (FIG. 5D) on thedie 34 (FIG. 5D). The access openings 54 in the polymer substrates 32have peripheral outlines that are larger than the peripheral outlines ofthe end portions 50 of the conductors 36 on the polymer substrates 32.The end portions 50 thus overhang the access openings 54 in a mannerthat is similar to beam leads on TAB tape. The access openings 54 can beformed by laser machining, punching or etching the polymer substrates32. In addition, the access openings 54 can be formed either prior to,or after, formation of the conductors 36 on the polymer substrates 32.

Referring to FIG. 2F, a single ball bonding pad 44 of a conductor 36 onthe polymer substrate 32 is illustrated in cross section. The ballbonding pads 44 can be formed of a same metal as the conductors 36,preferably at the same time as the conductors 36 are formed on thepolymer substrate 32. The ball bonding pads 44 can also be plated with ametal, such as Ni or Au, to facilitate a subsequent solder reflowprocess wherein the ball contacts 56 (FIG. 5A) will be bonded to theball bonding pads 44. Depending on the size and the pitch of the ballcontacts 56 (FIG. 5A) in the grid array for the package 38 (FIG. 5B), arepresentative diameter of the ball bonding pads 44 can be from about0.22 mm to 1.0 mm.

As also shown in FIG. 2F, the polymer substrate 32 includes a pattern ofball openings 58 in alignment with the ball bonding pads 44. The ballopenings 58 provide access through the polymer substrate 32 for bondingthe ball contacts 56 to the ball bonding pads 44. The ball openings 58can be formed at the same time as the access openings 54 by lasermachining, punching or etching the substrates 32. Preferably the ballopenings 58 have a peripheral outline that is about the same as the ballbonding pads 44.

Referring to FIGS. 3A-3D, steps in a method for fabricating a pluralityof semiconductor packages 38 (FIG. 5A) using the interconnect 30. InFIGS. 3A-3D, a segment of one substrate 32 on the interconnect 30 isillustrated schematically.

Initially, as shown in FIG. 3A, the interconnect 30 can be providedsubstantially as previously described, and shown in FIGS. 2-2F. Thesubstrate 32 on the interconnect 30 includes access openings 54 and ballopenings 58. In addition, patterns of conductors 36 are attached to thesubstrate 32. The conductors 36 include end portions 50 aligned with theaccess openings 54 through the substrate 32. The end portions 50 includebonding vias 42 formed and sized as previously described. The conductors36 also include ball bonding pads 44 aligned with the ball openings 58through the polymer substrate 32.

Next, as shown in FIG. 3B, for attaching the polymer substrate 32 to thedie 34 (FIG. 3C), an adhesive layer 62 can be formed between the die 34and the polymer substrate 32. In FIG. 3B, the adhesive layer 62 isinitially shown as being formed on the polymer substrate 32. However,the adhesive layer 62 can also be initially formed on the die 34. Theadhesive layer 62 can comprise a die attach adhesive such a silicone,epoxy, polyimide or acrylic material. The adhesive layer 62 is appliedsuch that the bonding vias 42 on the conductors 36 are unobstructed byadhesive material.

Next, as shown in FIG. 3C, the polymer substrate 32 and the die 34 areadhesively bonded using the adhesive layer 62. For some adhesivematerials, a curing step can also be performed using localized heating,or heating in an oven. In FIG. 3C, the bond pads 46 are embedded in adie passivation layer 64, which is placed in physical contact with theadhesive layer 62. Prior to bonding the die 34 to the polymer substrate32, the bond pads 46 on the die 34 are aligned with the bonding vias 42on the polymer substrate 32. Alignment can be accomplished using a splitoptics system such as one used in an aligner bonder tool, or using analignment fence or jig.

Next, as shown in FIG. 3D, the metal bumps 60 are formed in the bondingvias 42 bonding the end portions 50 of the conductors 36 to the bondpads 46 on the die 34. The access openings 54 provide access through thesubstrate 32 for forming the metal bumps 60. The metal bumps 60 can beformed using a conventional wire bonding tool 68 configured forthermocompression bonding (T/C), thermosonic bonding (T/S), or wedgebonding (W/B) of a metal wire 66. Suitable materials for forming themetal bumps 60 include gold, palladium, silver and solder alloys.

The metal bumps 60 can also be constructed using a solder ball bumperapparatus rather than a wire bonding tool. A solder ball bumperapparatus attaches pre-formed solder balls to metal pads, such as bondpads on a die or land pads on a substrate, using a reflow process. Arepresentative solder ball bumper apparatus with a laser reflow systemis manufactured by Pac Tech Packaging Technologies of Falkensee,Germany. If a solder ball bumper is employed to form the metal bumps 60,the bonds pads 46 can include one or more outer layers to provide adiffusion barrier (not shown). For aluminum bond pads 46 suitablediffusion barrier metals include Ni-Au and Pd. Such a diffusion barriercould be used to prevent diffusion between the metal bumps 60 and thebond pads 46, and to improve the reliability and electrical performanceof the metal bumps 60.

As also shown in FIG. 3D, following formation of the metal bumps 60, theball contacts 56 can be bonded to the ball bonding pads 44 on theconductors 36. Preferably the ball contacts 56 comprise solder ballsformed of a suitable solder alloy (e.g., 95%Pb/5%Sn, 60%Pb/40%Sn,63%In/37%Sn, or 62%Pb/36%Sn/2%Ag).

A solder reflow process can be used to bond the ball contacts 56 to theball bonding pads 44. Prior to the solder reflow process, solder fluxcan be deposited on the ball bonding pads 44 and on the ball contacts56. The ball contacts 56 can then be placed on the ball bonding pads 44,and a furnace used to form metallurgical solder joints 70 between theball contacts 56 and the ball bonding pads 44. During bonding of theball contacts 56, the ball openings 58 in the polymer substrate 32facilitate alignment of the ball contacts 56 to the ball bonding pads44. In addition, in the completed BGA package 38, the polymer substrate32 insulates adjacent ball contacts 56 and insulates the conductors 36from the ball contacts 56.

Following bonding of the ball contacts 56, the interconnect 30 can besingulated into a plurality of separate packages 38 by punching,shearing or cutting the polymer substrates 32 from the interconnect 30.If a wafer level fabrication process is employed, singulation can beaccomplished by separating the dice 34 and packages 38 from the waferusing a diamond tipped saw.

Referring to FIGS. 4A-4C, an alternate embodiment process forfabricating semiconductor packages using the interconnect 30 isillustrated. Initially as shown in FIG. 4A, the polymer substrate 32 isprovided substantially as previously described. In addition, a bumpeddie 34B is provided. The bumped die 34B includes solder bumps 74 formedon bond pads 46A of the die 34B. During adhesive bonding of the bumpeddie 34B to the polymer substrate 32, the solder bumps 74 are aligned andplaced through the bonding vias 42 on the conductors 36.

Next, as shown in FIG. 4B the solder bumps 74 are reflowed to formreflowed solder bumps 78RF. The reflowed solder bumps 78RF fill thebonding vias 42 and physically and electrically bond the end portions 50of the conductors 36 to the bond pads 46A. The reflow process can beperformed using localized heating with a thermode or by global heatingin an oven. Following the reflow process the ball contacts 56 can bebonded to the ball bonding pads 44 substantially as previouslydescribed.

Next, as shown in FIG. 4C, an encapsulant 76 can be formed on thereflowed solder bumps 78RF for protecting and electrically insulatingthe reflowed solder bumps 78RF. The encapsulant 76 can comprise anepoxy, silicone, polyimide or room temperature vulcanizing materialapplied through a nozzle as a glob top.

The encapsulant 76 can also be in the form of a solder mask, such as ablanket deposited photoimageable resist blanket, which can be exposedthrough a mask, then developed in a required pattern and with requiredfeatures (e.g., openings). One suitable resist is commercially availablefrom Taiyo America, Inc., Carson City, Nev. under the trademark“PSR-4000”. The “PSR-4000” resist can be mixed with an epoxy such asepoxy “720” manufactured by Ciba-Geigy (e.g., 80% PSR-4000 and 20% epoxy“720”). Another suitable resist is commercially available from Shipleyunder the trademark “XP-9500”. Although not shown, an encapsulate canalso be formed over the metal bump 60 of the previous embodiment.

Referring to FIGS. 5A-5C, the completed BGA package 38 is illustrated.The BGA package 38 includes the semiconductor die 34 and the polymersubstrate 32 adhesively bonded to the die 34. The die 34 includes thebond pads 46 (FIG. 5D) in electrical communication with integratedcircuits contained on the die 34. The BGA package 38 also includes theball contacts 56 bonded to the polymer substrate 32. The ball contacts56 are arranged in a dense array such that the BGA package 38 can besurface mounted to a mating component such as a printed circuit board.

As shown in FIG. 5C, the conductors 36 on the polymer substrate 32provide electrical paths from the bond pads 46 on the die 34 to the ballcontacts 56 on the polymer substrate 32. In addition, as shown in FIG.5D, the metal bumps 60 bond the end portions 50 of the conductors 36 tothe bond pads 46 on the die 34.

Thus the invention provides an improved interconnect and an improved BGApackage. Also provided is an improved method for fabricating BGApackages using the interconnect. Although the invention has beendescribe with reference to certain preferred embodiments, as will beapparent to those skilled in the art, certain changes and modificationscan be made without departing from the scope of the invention, asdefined by the following claims.

We claim:
 1. A method for fabricating a semiconductor packagecomprising: providing a semiconductor die comprising a face and aplurality of pads on the face; providing a polymer substrate comprisingat least one opening configured for alignment with the pads, and aplurality of conductors having portions with bonding vias therethroughaligned with and overhanging the opening; adhesively bonding thesubstrate to the face of the die with the opening in the substrate andthe bonding vias in the conductors aligned with the pads on the die; andforming metal bumps in the bonding vias, on the portions of theconductors, and on the pads, to physically bond and electrically connectthe conductors and the pads, with the opening in the substrate providingaccess for forming the metal bumps.
 2. The method of claim 1 furthercomprising forming a plurality of external contacts on the conductors.3. The method of claim 1 wherein the substrate includes a plurality ofsecond openings configured to provide access to the conductors forbonding a plurality of external contacts to the conductors.
 4. Themethod of claim 1 wherein the forming the metal bumps step comprisesplacing a wire bonding tool through the opening in the substrate.
 5. Themethod of claim 1 wherein the forming the metal bumps step comprisesbonding solder balls in the bonding vias, on the portions of theconductors and on the pads on the die using a solder reflow process. 6.The method of claim 1 wherein the forming the metal bumps step comprisesbonding solder balls in the bonding vias, on the portions of theconductors and on the pads on the die using a ball bumper apparatus. 7.A method for fabricating a BGA semiconductor package comprising:providing a semiconductor die comprising a face and a plurality of padson the face; providing a polymer substrate comprising a plurality offirst openings configured for alignment with the pads on the die, aplurality of second openings in a grid array, and a plurality ofconductors having bonding pads and portions aligned with the firstopenings having bonding vias therethough; bonding the substrate to theface of the die with the bonding vias in the portions of the conductorsand the first openings in the substrate aligned with the pads on thedie; forming metal bumps in the bonding vias, on the portions, and onthe pads, to physically bond and electrically connect the conductors tothe pads, with the first openings in the substrate providing access forforming the metal bumps; and forming external contacts on the bondingpads with the second openings providing access for forming the externalcontacts.
 8. The method of claim 7 wherein the bonding step comprisesforming an adhesive layer between the face of the die and the substrate.9. The method of claim 8 wherein the forming the metal bump step isperformed by reflow bonding solder balls.
 10. The method of claim 8wherein the metal bumps comprise a metal selected from the groupconsisting of gold, palladium, silver and solder alloys.
 11. A methodfor fabricating a BGA semiconductor package comprising: providing asemiconductor die comprising a face and a plurality of metal bumps onthe face; providing a polymer substrate comprising at least one openingconfigured for alignment with the metal bumps on the die, and aplurality of conductors having portions overhanging the opening andincluding bonding vias therethrough; adhesively bonding the substrate tothe face of the die with the bonding vias in the portions of theconductors and the opening in the substrate aligned with the metal bumpson the die; and reflowing the metal bumps into the bonding vias and ontothe portions of the conductors to physically bond and electricallyconnect the conductors to the die.
 12. The method of claim 11 furthercomprising forming an encapsulant in the opening in the substrate. 13.The method of claim 11 further comprising providing the conductors withbonding pads and bonding the external contacts to the bonding pads. 14.A method for fabricating a semiconductor package comprising: providing asemiconductor die comprising a face and a plurality of pads on the face;providing a polymer substrate having at least one opening therethroughconfigured for alignment with the pads on the die and a plurality ofball bonding openings in a grid array; providing a plurality ofconductors on the substrate having end portions with bonding viastherethrough aligned with and overhanging the opening in the substrate;providing a plurality of bonding pads on the conductors; adhesivelybonding the polymer substrate to the face of the die with the bondingvias on the end portions of the conductors aligned with the pads on thedie; forming metal bumps in the bonding vias, on the end portions, andon the pads to physically bond and electrically connect the conductorsto the pads with the opening in the substrate providing access forforming the metal bumps; and then bonding a plurality of externalcontacts through the ball bonding openings in the substrate to theconductors.
 15. The method of claim 14 wherein the end portions of theconductors have a first peripheral size corresponding to a secondperipheral size of the pads on the die.
 16. The method of claim 14wherein the forming the metal bumps step is performed by placing abonding tool through the opening in the substrate.
 17. The method ofclaim 14 wherein the forming the metal bumps step comprises providing awire bonding tool, placing the wire bonding tool through the opening inthe substrate and then using the wire bonding tool to bond the metalbumps to the pads on the die and to the end portions of the conductors.18. The method of claim 14 wherein forming the metal bumps stepcomprises providing a solder ball bumper tool and placing the toolthrough the opening in the substrate.
 19. The method of claim 14 whereinthe external contacts comprise balls in a ball grid array.
 20. Themethod of claim 14 further comprising providing the pads on the die withdiffusion barriers configured to prevent diffusion of the metal bumpsinto the pads.
 21. The method of claim 14 wherein the providing thepolymer substrate step comprises providing a plurality of substrates ona strip of material.
 22. The method of claim 14 the first portions ofthe conductors and the bonding vias in the end portions have a generallysquare peripheral shape.
 23. The method of claim 14 wherein the pads onthe die are provided in a single row along a center line of the die.